EH12, EH17, EH25 - Small Engine Discount

5-5 BREAK-IN OPERATION
An engine that has been completely overhauled by being fitted with a new piston, rings, valves and
connecting rod should be throughly RUN- IN before being put back into service. /“
Good bearing surfaces and running clearances between the various parts can only be established by
operating the engine under reduced speed and loads for a short period of time.
While the engine is being tested, check for oil leaks.
Make final carburetor adjustment and regulate the engine operating speed.
Steps
Load
Engine speed
Time
Step 1
No load
2500 rpm
10 rnin
Step 2
No load
3000 rpm
10 min
Step 3
No load
3600 rpm
10 min
EH12 1.4
Step 4
EH17 2.0
3600 rpm 30 min
EH25
3.2
EH12
2.8
EH17 4.0
Step 5 3600 rpm 60 min
EH25 6.4
6. IGNITION SYSTEM
6-1 TYPE OF IGNITION SYSTEM
EH 12 employs the U. T. C. I. (Universal type Transistor Controlled Ignition) pointless ignii .ion system.
El417 and E325 have the T. I. C. (Transistor Controlled Ignition) pointless ignition system.
As optional parts, these ignition system may be implemented with lamp coil, charge coil and excitor coil.
6-2 BASIC THEORY
‘1’0 ensure the easy startability of the engine, the step advancing ignition timing system is incorporated in
the ignition coil. ‘I’his system enables the engine to have basically two different ignition timings
according to the engine spced. Following are the explanation how the system works.
1) At lower speed of the engine
Kotation of the flywheel induces current I,, as this current flows through the base terminal of the
power transister, it is activated and the current Lz starts flowing.
As thc cnginc reaches thc ignition timing, the ignition timing control circuit for the lower engine speed
is activated and lcts the current I,: flow through the base terminal of the power transistor.
‘l’his gcncrates the collcctor current I, which will bypass the current I, and abruptly shut off the current
I? because the powcr transistor is turned off.
‘I’his sudden current change generates a big voltage on the secondary side of the ignition coil and
which sparks thc spark plug.
/”--
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